SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '305c994aed6464ab3cb3810089416a331b56486e5e301b5fcbf2eeaaeecd3c85' 
  AND token = 'RdeHngYGCrCGQS2XQKr+GDnZLW2LI/J6mdSwdAqn1aA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00031

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}